1. Technical Field
This invention relates to electric water pumps, and more particularly, to a water cooled electronic inverter for use in electric water pumps.
2. Background Art
FIGS. 1-4 show a pumping assembly 10 that is prior art as compared to the present application. The pumping assembly 10 is configured to be connected to a fluid circulation line of a swimming pool and/or other recreational body of water, such as a spa, etc. The pumping assembly 10 is typically connected to the fluid circulation line so as to pump dirty water for filtration and return clean water. Other devices might be connected along the fluid circulation line, such as sand filters, chlorinators, and other devices known in the art.
Referring to FIG. 1, the pumping assembly 10 includes a pump 12, a sealing plate 14, a motor 16, and a drive assembly 18. The pump 12 includes an inlet 20 for directing fluid from the fluid circulation line to a water chamber 24, and an outlet 22 for discharging the fluid from the water chamber 24 to the fluid connection line. The water chamber 24 includes a strainer basket for filtering water that flows into a chamber via the inlet 20. The motor 16 includes a shaft that protrudes into the water chamber 24, where the shaft drives an impeller (not shown) to pump fluids from the inlet 20, through the water chamber 24, and out the outlet 22. The sealing plate 14 blocks the water chamber 24 and has a through hole 26 to accommodate the motor shaft so that the motor 16 can drive the impeller within the water chamber 24. A fan shroud 30 is provided to cover one end of the motor 16. A base 32 is provided under the pump 12 and the motor 16 for providing stability thereto.
The drive assembly 18 is situated on an outer surface of the motor body. As shown in FIG. 2, the drive assembly 18 includes a housing 34 that encapsulates a first printed circuit board assembly 36 and a second printed circuit board assembly 38, which are in electrical communication with the motor 16. As shown, the first and second printed circuit board assemblies 36, 38 have polygonal shapes.
In the prior art, it is also known to cool an inverter by use of an external waterway bypass embedded into an inverter heatsink design to remove heat from power components. In these prior art systems, the pump in/out pressure difference is usually sufficient to achieve water flow required for cooling. In the prior art, it is also known to include a heat sink for allowing heat to be dissipated away from the printed circuit board assemblies. In operation, the prior art heat sink relies on water to flow through a space between the housing and the motor body.
In electronic water pump assemblies, electronic inverters having water cooling means are known in the art. In a typical electric water pump assembly, an electronic inverter converts main power supply into multiple phase output voltage, which is used by an electric pump to propel water, for example, to direct the water through a filtering and conditioning system. The electronic inverter is based on a printed circuit board that contains several electronic components. During inverter operations, heat is produced by the electronic components and must be dissipated to avoid inverter failure. In order to dissipate such heat, a pump assembly can include a water based cooling system that uses a dedicated water bypass. The dedicated water bypass diverts a portion of the pumped water into a manifold heatsink, where the diverted water removes the heat produced by the inverter electrical components.
These cooling systems, however, have several major disadvantages. First, operation of many of these cooling systems is based on water differential pressure created by running the pump. When the pump slows down, the operation decreases rapidly, thereby reducing cooling performance. Second, in these systems, the dedicated bypass is formed using additional waterways, which not only decrease overall pump efficiency due to reduction of differential pressure, but are also subject to failure as debris in the water may clog the manifold heatsink. Thus, these systems offer limited product reliability, as the narrower waterway paths may become clogged. Third, the mechanical design of these systems require more material to be used, as designated water pathways can require additional part machining processes and increase enclosure envelopes. These systems often include provisions for water bypass, as well a specially designed manifold heatsink that can ensure a perfect seal between the working inverter electronics and the water. Also, these systems involve the use of additional plumbing accessories, for example, to couple water flow between the pump and the heatsink. Thus, the cost of these systems is high. Fourth, these systems often require substantial manufacturing assembly effort, as well as burdensome maintenance and upkeep.